Fill in spider web cookies. Use tip 3, a cut parchment bag and full-strength white icing to outline spider webs. Use thinned white icing in cut parchment bag to fill in. Use tip 3, a cut parchment bag, and full-strength black icing to outline outside of web. Use tip 2, a cut parchment bag and full-strength black icing to pipe straight lines and inside of web.
Fill in spider cookies. Use tip 3, cut parchment bags and full-strength purple, orange, green and black to outline face and legs. Use tip 14, cut parchment bags and full-strength icing in matching colors to fill in face with stars. Or, use thinned matching colored icing in cut parchment bags to fill in face.
Let dry overnight.